Conventionally, there is known a fuel cell vehicle in which fuel hydrogen is chemically reacted with oxygen in air to yield electricity, and electricity thus derived is used to drive a motor, or a drive source, to obtain running power. Fuel cell vehicles are also called FC (Fuel Cell) vehicles, and a hydrogen tank for storing hydrogen gas is installed therein. Due to recent research and development relating to this hydrogen tank, hydrogen filling in a relatively short period of time and at a high pressure has become possible.
Fuel cell vehicles installed with abovementioned type of hydrogen tanks need to be refilled with hydrogen at a hydrogen supply station, for example, when hydrogen inside the tank decreases due to consumption by running. In such a case, a hydrogen supply nozzle is air-tightly connected to a filler port provided on the body of a fuel cell vehicle when it is at a stop at a hydrogen supply station.
Here, in the case where hydrogen leakage occurs while hydrogen is being filled into a vehicle, it is desirable that the hydrogen filling is immediately stopped to ensure safety, since hydrogen is a flammable gas.
As a related prior art document, a hose fitting for hydrogen filling having a built in emergency shutoff valve inside a nipple provided at an end portion of a filling hose connecting a hydrogen gas supply source and a filling tank is disclosed in Japanese Patent Laid-Open Publication No. 2009-121511 (Patent document 1). This emergency shutoff valve for hydrogen filling hose fitting is constructed such that the communication path is shut off when the pressure on the hydrogen gas supply source become lower than the hydrogen gas pressure inside the filling tank, and at least one of either the nipple or the emergency shutoff valve is constructed of non-metal material.
As another prior art document, a system state judgment method for a fuel cell system is disclosed in Japanese Patent Laid-Open Publication 2009-117191. This system state judgment method applies to a fuel cell system comprising: a fuel shutoff mechanism provided in a fuel path for supplying fuel to a fuel cell from a fuel tank; pressure detection means provided downstream of the fuel shutoff mechanism; and a pressure state judgment means for judging the pressure state based on information from the pressure detection means. The method includes the steps of: detecting pressure change, which is a step for detecting a pressure change value per a certain time period within a predetermined time after the shutoff mechanism has been shifted to a communicating state from a shutoff state by the pressure detection means; and judging an abnormal state when the pressure change value per the certain time period detected by the pressure detection means is less than the predetermined pressure change value, and therefore judging by the pressure state judgment means that the fuel inside the fuel tank is less than a predetermined volume. According to this document, the judgment of abnormal state, such as the fuel level decrease and valve leakage, can be quickly performed with one pressure detection mechanism.